摘要:

A review of the current research on the interference phenomenon between concurrent aerobic and strength training indicates modest support for the model proposed in this article. However, it is clear that without a systematic approach to the investigation of the phenomenon there is lack of control and manipulation of the independent variables, which makes it difficult to test the validity of the model. To enhance the understanding of the interference phenomenon, it is important that researchers are precise and deliberate in their choice of training protocols.Clear definition of the specific training objectives for strength (muscle hypertrophy or neural adaptation) and aerobic power (maximal aerobic power or anaerobic threshold) are required. In addition, researchers should equate training volumes as much as possible for all groups. Care needs to be exercised to avoid overtraining individuals. There should be adequate recovery and regeneration between the concurrent training sessions as well as during the training cycle. The model should be initially tested by maintaining the same protocols throughout the duration of the study. However, it is becoming common practice to use a periodised approach in a training mesocycle in which there is a shift from high volume and moderate intensity training to lower volume and higher intensity. The model should be evaluated in the context of a periodised mesocycle provided the investigators are sensitive to the potential impact of the loading parameters on the interference phenomenon. It may be that the periodised approach is one way of maintaining the training stimulus and minimising the amount of interference.The effects of gender, training status, duration and frequency of training, and the mode of training need to be regarded as potential factors effecting the training response when investigating the interference phenomenon. Other experimental design factors such as unilateral limb training or training the upper body for one attribute and the lower body for another attribute, may help establish the validity of the model.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

During the past decade, we have seen a growing number of individuals participating in sport and recreational activities. All indications show an increase in sport participation at every age level. However, the number of sport and recreational injuries as a result of this increase has also risen. Unfortunately, a primary cost related to injury recovery is the time lost from participating in and resuming normal functional activity. This has compelled health care professionals to seek more efficient and effective therapeutic interventions in treating such injuries. Hyperbaric oxygen (HBO) therapy may serve to provide a means of therapy to facilitate a speedier resumption to pre-injury activity levels as well as improve the short and long term prognosis of the injury.Although a growing interest in sports medicine is becoming evident in the literature, the use of HBO as an intervention in this field has received a great deal of cynicism. To date, numerous professional athletic teams, including hockey (NHL), football (NFL), basketball (NBA) and soccer (MLS), utilise and rely on the use of HBO as adjuvant therapy for numerous sports-related injuries acquired from playing competitive sports. However, to date, very little has been published on the application benefits of hyperbaric therapy and sports injuries. The majority of clinical studies examining the efficacy of HBO in treating soft tissue injuries have been limited in their sample size and study design. Further research needs to be conducted suggesting and validating the significant effects of this treatment modality and further grounding its importance in sports medicine.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

Ethical and methodological factors limit the availability of data on metabolic and hormonal responses to exercise in children and adolescents. Despite this, it has been reported that young individuals show age-dependent responses to short and long term exercise when compared with adults.Adenosine triphosphate (ATP) and phosphocreatine stores are not age-dependent in children and adolescents. However, phosphorus-31 nuclear magnetic resonance spectroscopy (31PNMR) studies showed smaller reductions in intramuscular pH in children and adolescents during high intensity exercise than adults. Muscle glycogen levels at rest are less important in children, but during adolescence these reach levels observed in adults.Immaturity of anaerobic metabolism in children is a major consideration, and there are several possible reasons for this reduced glycolytic activity. There appear to be higher proportions of slow twitch (type I) fibres in the vastus lateralis part of the quadriceps in children than in untrained adults, and anaerobic glycolytic ATP rephosphorylation may be reduced in young individuals during high intensity exercise. Reduced activity of phosphofructokinase-1 and lactate dehydrogenase enzymes in prepubertal children could also explain the lower glycolytic capacity and the limited production of muscle lactate relative to adults. These observations may be related to reduced sympathetic responses to exhaustive resistance exercise in young people.In contrast, children and adolescents are well adapted to prolonged exercise of moderate intensity. Growth and maturation induce increases in muscle mass, with proliferation of mitochondria and contractile proteins. However, substrate utilisation during exercise differs between children and adults, with metabolic and hormonal adaptations being suggested. Lower respiratory exchange ratio values are often observed in young individuals during prolonged moderate exercise. Data indicate that children rely more on fat oxidation than do adults, and increased free fatty acid mobilisation, glycerol release and growth hormone increases in preadolescent children support this hypothesis.Plasma glucose responses during prolonged exercise are generally comparable in children and adults. When glucose is ingested at the beginning of moderate exercise, plasma glucose levels are higher in children than in adults, but this may be caused by decreased insulin sensitivity during the peripubertal period (as shown by glucose:insulin ratios).ConclusionsChildren are better adapted to aerobic exercise because their energy expenditure appears to rely more on oxidative metabolism than is the case in adults. Glycolytic activity is age-dependent, and the relative proportion of fat utilisation during prolonged exercise appears higher in children than in adults.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS

摘要:

BackgroundThe ‘yips’ is a psychoneuromuscular impediment affecting execution of the putting stroke in golf. Yips symptoms of jerks, tremors and freezing often occur during tournament golf and may cause performance problems. Yips-affected golfers add approximately 4.7 strokes to their scores for 18 holes of golf, and have more forearm electromyogram activity and higher competitive anxiety than nonaffected golfers in both high and low anxiety putting conditions. The aetiology of the yips is not clear.ObjectiveTo determine whether the yips is a neurological problem exacerbated by anxiety, or whether the behaviour is initiated by anxiety and results in a permanent neuromuscular impediment.MethodsIn phase I, golf professionals assisted investigators in developing a yips questionnaire that was sent to tournament players (<12 handicap) to establish the prevalence and characteristics of the yips. Phase II measured putting behaviour in scenarios that contribute to the yips response. Four self-reported yips and 3 nonaffected golfers putted 3 scenarios using an uncorrected grip and a standard length putter. Heart rate was superimposed on the videotape and the putter grip was instrumented with strain gauges to measure grip force. Electromyograms and relative putting performance were also measured.ResultsThe questionnaire was sent to 2630 tournament players, of whom 1031 (39%) responded (986 men and 45 women). Of these, 541 (52%) perceived they experienced the yips compared with 490 (48%) who did not. Yips-affected golfers reported that the most troublesome putts were 3, 4 and 2 feet (0.9, 1.2 and 0.6 metres) from the hole. Fast, downhill, left-to-right breaking putts and tournament play also elicited the yips response. Golfers affected by the yips had a faster mean heart rate, increased electromyogram activity patterns and exerted more grip force than nonaffected golfers and had a poorer putting performance.ConclusionsFor <10 handicap male golfers and <12 handicap female golfers, the prevalence of the yips is between 32.5% and 47.7%, a high proportion of serious golfers. This high prevalence suggests that medical practitioners need to understand the aetiology of the yips phenomenon so that interventions can be identified and tested for effectiveness in alleviating symptoms. Although previous investigators concluded that the yips is a neuromuscular impediment aggravated but not caused by anxiety, we believe the yips represents a continuum on which ‘choking’ (anxiety-related) and dystonia symptoms anchor the extremes. The aetiology may well be an interaction of psychoneuromuscular influences. Future research to test the effect of medications such as β-blockers should assist in better identifying the contributions these factors make to the yips phenomenon.

ISSN:0112-1642    

出版商:ADIS    

年代:2000

数据来源: ADIS